How the web works provides a simplified view of what happens when you view a webpage in a web
browser on your computer or phone. This theory is not essential to writing web code in the short term, but before long you'll really start to benefit from understanding what's happening in the background. Computers connected to the internet are called clients and servers. A simplified diagram of how they interact might look like this:
The client and server we've described above don't tell the whole story. There are many other parts involved, and we'll describe them below. For now, let's imagine that the web is a road. On one end of the road is the client, which is like your house. On the other end of the road is the server, which is a shop you want to buy something from.
In addition to the client and the server, we also need to say hello to:
So what happens, exactly?When you type a web address into your browser (for our analogy that's like walking to the shop):
Order in which component files are parsedWhen browsers send requests to servers for HTML files, those HTML files often contain
DNS explainedReal web addresses aren't the nice, memorable strings you type into your address bar to find your favorite websites. They are special numbers that look like this: This is called an IP address, and it represents a unique location on the web. However, it's not very easy to remember, is it? That's why Domain Name Servers were invented. These are special servers that match up a web address you type into your browser (like "mozilla.org") to the website's real (IP) address. Websites can be reached directly via their IP addresses. You can use a DNS lookup tool to find the IP address of a website. Packets explainedEarlier we used the term "packets" to describe the format in which the data is sent from server to client. What do we mean here? Basically, when data is sent across the web, it is sent in thousands of small chunks. There are multiple reasons why data is sent in small packets. They are sometimes dropped or corrupted, and it's easier to replace small chunks when this happens. Additionally, the packets can be routed along different paths, making the exchange faster and allowing many different users to download the same website at the same time. If each website was sent as a single big chunk, only one user could download it at a time, which obviously would make the web very inefficient and not much fun to use. See alsoCreditIn this moduleWhat is a computer designed to request information from a server?Used in home and corporate networks, a client is any computer hardware or software device that requests access to a service provided by a server. Clients are typically seen as the requesting program or user in a client-server architecture.
Which type of address is used at the network layer to identify the receiving host?Which type of address is used at the Transport layer to identify the receiving application? The transport layer identifies the receiving application through the port number.
Which layer of the TCP IP model defines end to end forwarding of packets?Network Layer - The Network layer is responsible for end-to-end delivery of packets. IP running on a router examines the packet's IP destination and compares it to the IP routing table.
What term does the OSI model use that is different from the TCP IP model used to refer to frame packet and segment?While the TCP/IP model uses terms like segment, packet and frame to refer to a data packet defined by a particular layer, the OSI model uses a different term: protocol data unit (PDU). A PDU represent a unit of data with headers and trailers for the particular layer, as well as the encapsulated data.
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